what amprage are the 12 volt lights?
if we assume they are 15 amp a peice... 15*8=120.. thats alot of amps to be pulling....
you should find the specs for the lights. i have some big round lights i found from walmart that are fairly bright, they pull about 10 amps... 10*8=80

Voltage*amprage=watts so 80*120= 9600 watts....

You should find the specs on the bulbs.